The following question is based on the following alphabet series.
A  B  C  D  E  F  G  H  I  J  K  L  M
N  O  P  Q  R  S  T  U  V  W  X  Y  Z If the letters of the given alphabet interchange positions, so that A takes the place of Z and Z takes the place of A; B takes the place of Y and Y takes the place of B and so on, what will be the thirteenth letter from the right ?

Answer: A. M

The new alphabet series is :
Z  Y  X  W  V  U  T  S  R  Q  P  O  N
M  L  K  J  I  H  G  F  E  D  C  B  A

Counting from the right in the above series i.e., A, the thirteenth letter is M.